Adjunct in the chronic management of urea cycle disorders involving deficiencies of carbamylphosphate synthetase, ornithine transcarbamylase, or argininosuccinic acid synthetase, including neonatal-onset deficiency and late-onset disease with a history of hyperammonemic encephalopathy.
<20kg: use powder. Take in equally divided doses with each meal or feeding. Mix powder with food or liquid. <20kg: 450–600mg/kg/day. ≥20kg: 9.9–13g/m2/day. Max 20g/day.
Restrict dietary protein, may need to supplement with essential amino acids. CHF. Sodium retention with edema. Renal or hepatic insufficiency. Inborn errors of beta oxidation. Monitor serum levels of phenylbutyrate and metabolites, phenylacetate and phenylacetylglutamine. Plasma levels of ammonia, arginine, branched-chain amino acids, serum proteins: maintain within normal levels; plasma glutamine: maintain at <1000μmol/L. Elderly. Pregnancy (Cat.C). Nursing mothers.
May be potentiated by probenecid. Corticosteroids may increase plasma ammonia levels. Hyperammonemia possible with haloperidol and valproic acid.
Amenorrhea/menstrual dysfunction, acidosis, hypoalbuminemia, anemia, alkalosis, hyperchloremia, hypophosphatemia, increased alkaline phosphatase, increased liver transaminases, leukopenia, leukocytosis, decreased appetite, body odor, bad taste, taste aversion, others.